Combination fine tuning and slewing device



March 22, 1960 s. BROADHEAD, JR.. ETA!- 2,929,251

COMBINATION FINE mums AND SLEWING DEVICE Filed Nov. 24, 1958 Pa WEA'50pm r INVENTORS .SaMusL L. 81204011000 J0.

j A TTORNE Y United sates Patent" COMBINATION FINE TUNING AND SLEWINGDEVICE Samuel L.Broadhead, Jr., Cedar Rapids, and Harry Lehman, Marion,Iowa, assignors to Colims Radio Company, Cedar Rapids, Iowa, acorporation of Iowa Application November 24, 1958, Serial No. 775,755

2 Claims. (Cl. 74-103) This invention relates generally to improvementsin tuners for electronic equipment, and more particularly to a simpleand effective combined coarse and fine tuning mechanism.

The primary object of this invention is to provide an improved tuningmechanism including gearing active over a portion of its operation toefiect fine tuning and active over other portions of its operation toeffect coarse tuning.

A more specific object of this invention is to provide an improvedtuning mechanism including a fine tuning drive operative between twospaced, coarse drives with the drives being consecutively operable ineither direction.

Another object of this invention is to provide an improved tuningmechanism including plural power paths between an input drive shaft andan output shaft, one of the paths effecting coarse tuning and the otherpath being effective only during a portion of a power input cycle toeffect fine tuning between stages of coarse tun- With the foregoing andother objects in view, the invention resides in the followingspecification and appended claims, certain embodiments and details ofconstruction of which are illustrated in the accompanying drawingwherein the tuning mechanism comprising the invention is illustrated ina partially sectioned plan view.

Referring more particularly to the drawing, the tuning mechanismincludes a housing 1 to which is secured by any suitable means (notshown) a reversible driving motor 2. The motor 2 directly drives theinput shaft 3 of the tuning mechanism. The shaft 3 carries a drive gear4 which is of substantial length within the confines of housing 1.

Rotatably supported on housing 1 by suitable journals 5 and 6 is anoutput or driven shaft 7 which actuates condensers or inductors, notshown. Within the housing the shaft 7 fixedly carries a driven gear 8which includes an integral hub 9. As illustrated, the hub 9 of gear 8 ispositioned adjacent the inner wall of housing 1. Adjacent the journal 6the shaft 7 is provided with an integrally mounted abutment 10.Intermediate the face of gear 8 and the abutment 10 the shaft 7 isthreaded at 11 to receive in threaded relationship thereon a traversegear 12. The teeth 13 of gear 12 continuously mesh with the teeth ofdrive gear 4 over the full range of travel of the traverse gear betweengear 8 and abutment 10.

Spaced from the output shaft 7 and carried by journals 14 and 15 withinhousing 1 is an idler shaft 16. As illustrated, the shafts 3, 7, and 16are mounted in spaced parallel relationship with the shaft 7constituting in effect an intermediate shaft. The shaft 16 fixedlycarries a gear 17 of substantial length. The teeth of gear 17 mesh withthe teeth 13 of traverse gear 12 over a portion of its travel betweengear 8 and abutment 10. The period of engagement is controlled by thelength of gear 17. In the preferred design gear 17 is positioneddirectly opposite gear 4 and is somewhat shorter in the axial dimensionthan gear 4 so that traverse gear 12 will dis- 2,929,251 Patented Mar.22, teen terminals 23 and 24. A switch box 19 is connected to terminals23 and 24 and has a knob 20 movable from S or stop position to F orforward position or to R or reverse. Leads 22 connect the switch box 19to the motor 22.

The motor 2 may be controlled by knob 20 so that it runs forward,reverse, or is stopped.

When the gear 12 engages gear 17 the shaft 7 will be driven slower thanwhen gear 12 is out of engagement with gear 17. Thus, by controlling thedirection of rotation of the motor 2, the relationship between shafts 3and 7 may be varied.

The operation of the tuning mechanism should be obvious to one skilledin the art. With the traverse gear 12 in the position shown in unbrokenlines, assume that a signal is sent to motor 2 to adjust the tuning bymoving shaft 7 over a considerable frequency range. Depending on thedirection of rotation of gear a, the gear 12 will be rotated'and hencemoved axially of the shaft 7 along thread 11 in one direction or theother and eventually will reach either of the two broken line positionsindicated for gear 12. While gear 12 remains in mesh with gear 17, adrive path is maintained from gear 4, through gears 12, 17 and 18 tooutput or driven gear 8. This drive path constitutes a fine tuning pathfor the output shaft 7 and assist in reaching a precise frequency level.If the signal received by motor 2 is sufiicient to drive the tuner to awidely spaced position from its previous setting, then a rapid movementof shaft 7 is desired to reach the new position as quickly as possible.Rapid traverse is obtained in this tuning mechanism as soon as thetraverse gear engages either the face of gear 8 or the abutment 10, forat this position the teeth 13 of gear 12 are out of mesh with gear 17and the drive path is directly from gear 4 to the gear 12, now lockedagainst axial movement, and to the shaft 7. The shaft 7 may overshootthe newly signalled tuning position. If this occurs, the knob 20 maybemoved to change the direction of rotation of motor 2. The traverse gear12 will move away from its locked position against the gear 8 orabutment 10 and the teeth 13 will reengage gear 17 to effect a finetuning drive so that a true or precise null may be reached at the newfrequency level.

Thus it should be apparent to one skilled in the art that the tuningmechanism provides a simple and effective part of drive paths co-actingwith one another so that a fine tuning movement of an output shaft iseffective, in either direction of rotation of an input shaft, betweentwo effective coarse tuning motions, to enable the mechamsm to rapidlyseek an approximate new frequency level and then seek out an exact ornull position.

It is realized that the details of the invention may be subject tovarious structural modifications well within the knowledge of theseinventors, who intend only to be limited to a liberal interpretation ofthe appended claims,

We claim:

1. A tuning control mechanism for radio equipment comprising an inputshaft, a drive gear of substantial length mounted on said input shaft,an output shaft, said output shaft including a pair of spaced stop meansand a threaded periphery between the stop means, a traverse gear mountedin threaded engagement with the output shaft between the stop means andbeing in continuous engagement with the drive gear, an idler shaft, 2.gear mounted on the idler shaft for limited engagement with the traversegear, a pinion gear mounted on the idler shaft, and an output drivinggear mounted on the output 5; shaft and engaging the"pinion gear, saidoutput gear functioning as one of the stop means, said drive gear actingin either direction of rotation to move the traverse gear lengthwise ofthe output shaft, said traverse gear when driven'against either stopmeans creating a coarse movement gear path for the output shaft and saidtraverse gear in its limited engagement with idler shaft gear duringmovement along the output shaft between the stop means creating a finemovement gear path for the output shaft.

2. A tuning control mechanism for radio equipment comprising a driveshaft, first gear means carried by said drive shaft, an intermediateshaft constituting an output shaft mounted in said mechanism in spacedrelationship to said first gear means, said intermediate shaft beinghelically threaded over its length, a second gear means mounted on saidintermediate shaft and having internal threads mating with the threadsof said shaft, said second gear means being in continuous engagementwith said first gear, an idler shaft carriedihy said mech'a- 20 nism, athird gear carried by said idler shaft, said third sion of theintermediate shaft, a pinion gear carried .by

said idler shaft, and a driven gear carried by said inter mediate shaft,said driven gear and said pinion gear being in continuous engagement,sad first gear means acting through said second and third gears and thepinion and driven gears to rotate the intermediate shaft to obtain afine tuning output, said first gear acting through said second gear todirectly drive the intermediate shaft for coarse tuning when said secondgear is moved from engagement with the third gear means in eitherdirection of travel by the threaded intermediate shaft.

References Cited in the file of this patent FOREIGN PATENTS GreatBritain Jan. 8, 1958

